Electrodeposition of nickel



United States Patent 3,002,904 ELECTRODEPOSITIGN 0F NICKEL Donald Gardner Foulke, Watchung, Otto Kardos, Red Bank, and Herman Koretzky, Belleville, N.J., assignors to Hanson-Van Winkle-Munning Company, a corporation of New Jersey No Drawing. Filed-Sept. 26, 1958, Ser. No. 763,456 16 Claims. (Cl. 204-49) This invention relates to electroplating and, more particularly, to electrodepos'iting nickel from an aqueous acidic nickel plating bath. The invention is based on the discovery that the bisulfite addition products of acetylenic compounds, when incorporated in a nickel electroplating bath, are remarkably effective for promoting the formation of very bright and ductile electrodeposits of nickel over a wide current density range and, moreover, that certain of these bisulte adducts also function as Class I (or primary) brighteners in nickel plating baths and are capable of extending the brightening capacity of a large number of Class II (or secondary) brightening compounds.

Theoretically, there are at least two possible bisulfite addition products whichmay be formed from a given acetylenic compound. Disregarding the numerous optical and geometrical enantiomorphs which chemical theory predicts may be formed, the addition of a hisulfite to an acetylenic bond proceeds in two successive stages, the first of which results in the formation of an initial bisulfite addition product which in turn reacts, in the second stage, to form a second bisulfite adduet. The extent of the reaction is dependent upon and therefore controlled by the molar proportions of hisulfite present in the reaction mixture. Although the proof of structure of each of the two adducts is far from conclusive, the initial bisulfite addition product of an acetylenic compound appears to be an a,t3-unsaturated sulfonic acid (or sulfonate), which is capable of undergoing further addition in the presence of excess hisulfite to form the second adduct. The apparent structure of this second hisulfite addition product is that of a saturated disulfonic acid (or sulfonate), in which the sulfonic acid (or sulfonate) groups are vicinal.

Because almost any acetylenic compound can be made to undergo hisulfite addition, that is, can be made to react with a compound capable of forming a chain-carrying sulfite radical to form one or more hisulfite addition products, no single common structural feature can be advanced to unequivocally characterize all of these adducts. At the present time, the only convenient characterization of the adducts is based on designating the proportionate amount of hisulfite (or of any compound capable of forming a chain-carrying sulfite radical) used in the reaction mixture. For example, the addition of a single equivalent of bisulfite to an acetylenic bond yields a compound which may be termed a monoadduct, while further addition of a second equivalent of hisulfite to this compound results in the formation of a second adduct which, for convenience, is designated as a biadduct, both adducts probably containing impurities.

Following an exhaustive investigation into the chemistry of hisulfite addition to acetylenic bonds, it has been discovered that the bisulfite addition products prepared by reacting a water-soluble acetylenic compound with 2N times an equivalent weight of a compound capable of 3,002,904 Patented Oct. 3, 1961 deposits are formed when the hisulfite addition product is employed in conjunction with a Class II (or secondary) brightener, for the combined use of the hisulfite adduct and the Class II brightener has been found to exert a synergistic effect on the brightening capacity of the bath as compared with the use of'either additive alone.

Only very small quantities of these hisulfite addition products are required in the plating bath for, in general, concentrations as low as 0.1 millimole per liter have been found to be effective. In many cases, however, at least 1 millimole per liter of the hisulfite addition products should be employed to secure the full benefit of their presence in the bath. There appears to be no critical upper limit on the concentration of these hisulfite addition products save solubility, but there is generally no advantage in employing more than 300 millimoles per liter, and in most plating baths substantially the full benefit of its presence is achieved with 50 millimoles per liter, or even less.

Any hisulfite addition product prepared by reacting a water-soluble acetylenic compound with 2N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, may be selected for inclusion in the plating solution. Particularly satisfactory results have been obtained by using the hisulfite addition products prepared from tit-substituted or a,u-disubstituted acetylenic compounds, both of which contain a functional group on a carbon atom vicinal to the acetylenic bond. It is of course necessary that the particular tit-substituted or a,a-disubstituted acetylenic compound used to prepare the hisulfite adduct contains at least one acetylenic bond which is neither sterically nor electronically hindered from undergoing reaction with a chain-carrying sulfite radical, and that the hisulfite adduct be capable of being dissolved in acid without undergoing decomposition.

A preferred process according to this invention for producing bright nickel deposits comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 250 millimoles per liter of the hisulfite addition product of an lit-substituted acetylenic compound and 2N times an equivalent weight of -a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound. 'The (at-substituted acetylenic' compounds used in preparing this hisulfite adduct all contain the structural configuration in which R is a substituent of the group consisting of hydrogen, alkoxy, formoxy, alkenoxy, halogen, and polyoxy. groups having the structure R0 O--[OH1( ]HO]nH in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20. In addition, R may also be an amino group having the following structure in which each of R and R" are either hydrogen, alkyl, or hydroxyalkyl.

Preparation of the bisulfite addition products is generally accomplished by refluxing an aqueous solution containing both the acetylenic compound and an alkali metal bisulfite (or sulfite) until most of the bisulfite (or sulfite) ions have been consumed. The rate at which bisulfite ion is consumed in the reaction mixture is accelerated by passing gaseous oxygen through the mixture or by adding a trace amount of a free radical initiator (i.e., benzoyl peroxide) to the reactants; the rate is sharply diminished, on the other hand, by adding trace amounts of free radical inhibitors, such as hydroquinone and similar antioxidants, to the reaction mixture. From these observations, it may be concluded that bisulfite addition to an acetylenic bond occurs primarily by a radical chain process, in which the chain-carrying steps may be postulated as proceeding via the following reaction sequence:

The exact nature of the chain-carrying sulfite radical is not actually known, since a similar chain involving HSO can be written. Both species (80 -9 and HSO;;-) have been proposed for the autoxidation of bisulfite and sulfite ions by oxygen, and hence either may be the transitory intermediate which adds to the acetylenic bond. No matter what the transitory intermediate radical, however, any compound which is capable of forming a chain-carrying sulfite radical may be used to form the bisulfite adduct. The term compound capable of forming a chain-carrying sulfite radical denotes the alkali metal or metal bisulfites, sulfites, and metabisulfites, as well as sulfurous acid or gaseous sulfur dioxide. All of these compounds may be used to form bisulfite adducts of acetylenic compounds which, in turn, may be used in nickel plating baths in accordance with this invention.

Even though all of the available evidence indicates that bisulfite addition to an acetylenic bond is radical in nature, and that consequently the predominant product formed when. excess bisulfite is used is the corresponding vicinal disulfonic acid (or disulfonate), the possibility that bisulfite or sulfite ions form charge-transfer complexes with acetylenic bonds, or that bisulfite or sulfite ions undergo ionic addition to an acetylenic bond, cannot be completely dismissed.

After the bisulfite adduct has been prepared, the reaction mixture may be added directly (or decolorized and then added directly) to the nickel plating bath or, alternatively, the bisulfite addition product may be recovered from the reaction mixture (either by crystallization or precipitation), and then added to the plating bath, the same plating results being obtained in either case. Although the bisulfite addition products may be used in concentrations as high as 300 millimoles per liter, or even more, there is no particular advantage to be gained from the higher concentrations, and the biadducts are preferably used in the range of concentrations from about 1 to about 50 millimoles per liter, or even in the relatively narrow range from 1 to 10 millimoles per liter.

The bisulfite addition products prepared from ot-Sllbstituted acetylenic compounds have been found to be unusually efiective brightening agents, especially when used in a plating bath in conjunction with various Class II brightener additives. Particularly satisfactory results have been obtained from the bisulfite addition products prepared from tat-substituted acetylenic compounds having a structure represented by the formula $1! in which each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted, alkoxy-substituted, and aminosubstituted alkyl, alkenyl, and alkynyl groups, and R is a substituent of the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, hydroxy-substituted, alkoxysubstituted, and amino-substituted alkenyl and alkynyl groups. In addition, R may also be a substituted-alkyl group having the structural configuration R4 BIS-7(5- in which each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted, alkoxy-substituted, and amino-sub: stituted alkyl, alkenyl, and alkynyl groups. Each of R n Rh n e above rm s a e ubs ue s Qt th r up consisting of hydroxy, alkoxy, formoxy, alkanoxy, haiogen, and polyoxy groups having the structure Ra O-[CHz( 3H,-O]n.-H

in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1- to 20. MoreoverfR and R may also be an amino group having the structure in w h eac of and. R" r u uent at th r up consisting of hydrogen, alkyl, and hydroxyalkyl. The compounds listed in Table I are examples of various a-substituted acetylenic compounds which may be used to prepare the bisulfite addition products (biadducts) which, in turn, may be employed successfully in embodimer ts of this invention.

TABLE I tat-Substituted qcetylenic compounds The bisulfite addition products of each of the acetylenic compounds listed in Tables I and 11 are. prepared by re. fluxing an aqueous solution of the particular acetylenic compound with two equivalents (for each acetylenic bond in the acetylenic compound) of a compound capable of forming a chain-carrying sulfite radical, preferably an alkali metal bisulfite. These bisulfite addition products, or diadducts, readily dissolve without decomposition in aqueous aeidic nickel plating baths, and are unusually eifective as carrier brightening agents in. such baths in promoting the formation of bright and ductile nickel electrodeposits over wide current density ranges and in extending the brightening range of a large number of secondary (Class II) brightener additives.

Secondary brightener additives, the synonym of which is Class II'brighteners, are those which, when dissolved in a nickel plating bath, promote the formation of an electrodeposit having a brighter and more lustrousflsnrface than the basis metal itself prior to electrodeposition but which, in general, must be used in conjunction with a primary (or *carrier) brightening agent. Plating baths containing the bisulfite addition producis, or diadducts, of y e ic comp u d and a C as II. b s s h a much wider brightening capacity and more often yield brilliant electrodeposits than baths which contain either diti lone- Outstanding results have been obtained when watersoluble acetylenic compounds, particularly the oxygencontaiuingor the amino-substituted acetylenic compounds, or both, are used in the plating bath as. Class II brighteners in conjunction with the bisulfite addition products.

Examples of Class II acetylenic brightening agents which h e been d susce fiilly i emb ime ts of t invention include the o -substituted and ,e'-disubstituted acetylenic compounds listed in Tables I and II. These water-soluble acetylenic compounds may be used over a wide range of concentrations, but when they are used in conjunction with a bisulfite addition product (not necessarily of the same acetylenic compound), the preferred range in concentration is from about 1 to 25 niillimoles per liter.

Many other secondary brightening compounds may be used in the plating bath' in combination with the bisulfite addition products, and include such Class II brighteners as unsaturated N-oxides (e.g., pyridine-N-oxide); aromatic phosphinic acids (e.g., phenylphosphirn'c acid) a-amino-N-heterocyclic compounds (e.g., qefillillfit) pyri; dines and a-pyrimidines); bis-pyridyls (e.g., 2,2'-dipyri dyl); olefinic alcohols (e.g., 2-butene-1,4-diol); the condensation products of tetraethylene-pentamine with acrylonitrile, methyl sulfate, epichlorohydrin, benzensulfonyl loride. or dimethylcmoraeetan pyridinium halides. (eg.,

ethylene bis pyridinium bromide, dirnethylene-bis-pyridininrn elrloride, and nitropyridinium pyrazole chloride); various azo compounds, such mono-, di-, and triaminoazobenzenes; halogenated carbonyls, such as chloral hys drate, bromal hydrate, and butylchloral hydrate; coumarin compounds; alkylated quinolinium halides (e.g., benzyl methyl quinolinium chloride); polyalkylene amines; and amino polyaryl methanes.

To illustrate the applicability of using the bisulfite addition products of acetylenic compounds in nickel electroplating baths, Table III summarizes the preparation of the bisulfite adducts of seven different acetylenic compounds which were employed in carrying out the examples of: the invention that are set forth below. Each of these bisulfite addition products was prepared by reacting 0.5. of an equivalent of the. acetylenic compound with [(2N) (0.5 equivalents of sodium bisulfite, where N is,

equal to the number of acetylenic bonds per molecule.

of the acetylenic, compound. Six of the acetylenic compounds were monoacetylenic (N =1), and hence only 1.0

equivalent weight of sodium. bisulfite was required for each reaction The n h. QQmPQundr howe e 8 poiyacetylenic (N=2) and therefore required 2.0 equivalents of sodium bisulfite for the reaction. In each case,- the reaction was carried out by refluxing a mixture of the acetylenic compound and sodium bisulfite in an aqueousmedium for a period of about 7 hours. At the end of this period and after cooling, an aliquot was withdrawn from the reaction mixture and titrated with a standardized iodine solution to determine the equivalents of sodium bisulfite which remained unreacted; this determination is reported in the third column of Table III. The reaction mixture, less the aliquot required for titration, was decolorized with activated carbon, filtered under suction,

and m hanol S QWIy added to. the filtrate to precipitate the bisulfite addition product. The precipitated bisulfite addition product was used without further purification.

TABLE III Preparation of bisulfite addition product (biqdduc!) of. various acetylenic compounds Equivalents used in reaction Equivalents of acetylenic Apetylenic compound I compound Z-butyne-kfidiol -R F PY r 1,4-di Q-hydroxyethoxy) -2-butyne 1,4-dichloro-2-butyne- 4-n1ethQXY-2-butyn-l-o1 3-methyl-1-butyn-3-0L. 2,4-hexadiyne-LG-diol-..

In each of the following examples of the invention, which are summarized in Tables IV and V, nickel was electrodeposited from a highly purified Watts plating bathhaving the following basic composition:

Grams per liter Nickel sulfate, NiSO -7H O 300 Nickel chloride, NiCl -6H O 45 Boric acid, H3BO 41.25

TABLE IV Effect of bisulfite addition products of acetylenic compounds on bright nickel plating Concentration of bisulfite adduct (mmoles/l.)

Properties oi eleetroplato Bisulfite addition product (biadduct) of Appearance Stress (l s/sq.

2-butyne-,4-1dio1 2-propyn- -o l,4-di (B-hydroxyethoxy) -2- b tyne u 1,4dichloro-2-butyne 4 4 Semi-bright Bright Semi-bright.

4-methoxy-2-butyn-1-ol 3-rnethyl-1-butyn-3-ol 2,4-hexadiyne-1,6diol The cumulative effect exerted by a water-soluble acetylenic compound in broadening the plating range of baths containing various bisulfite addition products (di adducts) is illustrated by the examples set forth in Table V below. Electroplates of nickel, deposited from a Watts plating bath (pH=3.2) containing 300. grams" per liter of nickel sulfate (NiSO -7H O), 45 rams per. liter ofnickel chloride. (NiCl r 611 0), 4.1.25 grams per liter of boric acid (H BO and varying concentrations of one of the bisulfite addition products described in Table III, increased in brilliance when a representative water-soluble acetylenic compound (2-butyne-1,4-diol) was used in conjunction with the bisulfite addition product. Plating operations were carried out in an open vessel on polished steel cathodes, using mild air agitation,

TABLE v Cumulative efiect of bisulfite addition products of acetylenic compounds on bright nickel plating cule of the acetylenic compound, said bisulfite addition product containing the structural configuration -CH--CH-(| 7 SO3M $05M R.

iniwhich *M is acation .substituent selected from the group consisting of hydrogen, alkali metals, ammonium,

magnesium, and nickel, R,, is a substituent of the group consisting of hydroxy, alkoxy, tormoxy, alkanoxy, halo gen, polyoxy groups having the structure v R0 7 a -'o -[cH,eH-o ..-n

in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and ammo groups having the structure inwhich each of R' and R" consisting of hydrogen, alkyl, and hydroxyalkyl, said 7 Cone. of (June. of Properties of Electroplate Bisulfite addition product (biadduet) bisulfite Z-butyneofadduct 1,4-di

(rnnioles/l.) (m1./l Appearance S r (l -l Leveling V sq. ft.) percent 2-butyne-1,4-diol 6 1. Bright 2-pr0py'n-1-o1 4. 4 1. 25 d0--.--..

1,4-di(fi-hydroxyethoxy) 4. 4 1. 25

1,4-dichloro-2-butyne 4. 4 1. 25

4-methoxy-2-butyn-1-oL 4. 4 1. 25

3-methyl-1-butyn-3- 4. 4 1. 25 2,4-hexadiyne-L6-diol 4. 4 1. 25 900 8 1 Concentration of 2-butyne-1,4-di0l was 9 percent by weight in aqueous solution.

Table V indicates that for optimum results the plating bath should contain both the bisulfite addition product and a Water-solubleacetylenic compound. The general principle illustrated in, Table V, that the platingrange of a bath containing a bisulfite addition product (diadduct) may be extended by the inclusion in that bath of a Class II brightener, one ex-ample of which are the acetylenic brightening agents, was repeatedly and consistently verified in another series of tests using a variety of secondary brighteners, including many representative straight nickelsulfate baths, in straight nickel chloride 60 baths, and in various other nickel plating baths based on using nickel formate, nickel sulfamate, or nickel fluoborate as thenickel saltwhichis dissolved in the aqueous acidic solvent. Consequently the invention is applicable to electrodeposition from any aqueous acidic solution. of one or more nickel salts. r

.We claim: 7 i

1. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution in which there is dissolved from about 1 to about 250 millimolesper liter of the bisulfite addition product of an rat-substituted acetylenic compound and 2N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecompound capable of forming a chain-carrying radical being selected from the group consisting of suifurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites.

2. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of atleast one nickel salt in which there is dissolved about 1' to about 250 millimolcs per liter of the'bisulfite addition product of an ot,cL'-diSllbstituted acetylenic compound and 2N times an equivalent weight of a compound capable" of forming a 'chain-' carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said bisulfi-te addition product containing the structural, configuration are substituents of the group:

inwhich each of R and R" are substituents of the group consisting of hydrogen, alkyl, and hydroxyalkyl, said compound capable of forming a chain-carrying radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and meta-bisulfites.

, ;3,. The process for producing bright nickel deposits which comprises electrodepositing nickel vfrom an aqueous, acidic solution in which there is dissolved from about 1 to about 250 mill-imoles per liter of the bisulfite addition product of an unsubstituted acetylenic compound and 2 N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenie compound, said bisul-fite', addition product having a structure represented by the formula R1 R,H0H-iJ-Rr solivr 03M R.

in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted, alkoxy-substituted, and amino-substituted alkyl, alkenyl, and alkynyl groups, R, is a substituent of the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, hydroxy-substituted, alkoxy-subst-ituted, and amino-substituted alkenyl and alkynyl groups, and substitutcd-alkyl groups having the structural configuration in which each of R and R are substituents. of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted, alkoxy-substituted, and amino-substituted alkyl, alkenyl, and alkynyl groups, and each of R, and R are, substituents of the group consisting of y roxy, l x formo y, ano y, alogen, po y y groups having the structure in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glyci yl, and n is an integer from 1 to 2 0, and amino groups having the structure in which each of R and R" are substituents of'the group consisting of hydrogen, alkYl, and hydroxyalkyl, said compound capable of forming a chain-carrying radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metaibisulfitest 4. The process for producing bright nickel depositswhich compriseslelectrodepositing nickel from an aqueous acidic solution of at least one nickel salt inwhich there is dissolved from about 1 to about 250 millimoles per liter of the bisulfite addition product of an a,u'- disubstituted acetylenic compound and 2N times an equivalent weight of a compound capable of forming a chaincarrying sulfite radical, where N is-equal to the number of acetylenic bonds per molecule of the acetylenic compound, said bisulfite addition product having a structure represented by the formula in" which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium,"

magnesium, and nickel, each of R R R and R are substituents. of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substitut-ed, alkoxysubstituted, and amino-substituted alkyl, aikenyl, and alkynyl groups, and each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy;

halogen, polyoxy groups having the structure 0[OH;( )H-O]s-H in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and amino groups having the structure N RII in which each of R and R" are substituents of the group consisting of hydrogen, alkyl, and hydroxyalkyl, said compound capable of forming a'chain-carrying radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisullites, and sulfites, and metabisulfites.

5. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition product has a structure represented by the formula R2 R3-oHcH-('1-R1 SOaM 805M OH 6. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition prod-- not has a structure represented by the formula 8. The process for producing bright nickel deposits according to claim 3, wherein the bisulfite addition product has a structure represented by the formula 9. The process for producing bright nickel deposits according to claim 4, wherein the bisulfite addition product hasa structure represented by the formula R4 R2 R,-t J-t 7H-0H-( :R|

s 803M sioiM H 10. The process for producing bright nickel deposits according to claim. 4, wherein the. bisulfite addition product has a structure represented by the formula R4 R: t R --c H---c :H0R1

b SOaM SOIM in which X is a hal'ogen.

It; The: process for producing bright nickel deposits 13 according to claim 4, wherein the bisulfite addition product has a structure represented by the formula 12. The process for producing bright nickel deposits according to claim 4, wherein the bisuliite addition product has a structure represented by the formula 13. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 0.1 to about 500 millimoles per liter of the bisulfite addition product of a water-soluble acetylenic compound and 2N times an equivalent Weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said compound capable of forming a chaincarrying radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said hisulfite addition product containing the structural configuration in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, and the vicinal carbon atoms to which each of the 80 M radicals are attached were originally acetylenic carbon atoms, and (b) from about 1 to about 250 millimoles per liter of a Water-soluble acetylenic compound.

14. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution in which there is dissolved (a) from about 1 to about 250 millimoles per liter of the bisulfite addition product of an a-substituted acetylenic compound and 2N times an equivalent Weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said compound capable of forming a chain-carrying radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroXy-substituted, alkoxy-substituted, and amino-substituted alkyl, alkenyl, and alkynyl groups, R, is a substituent of the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, hydroxy-substituted, alkoXy-substituted, and amino-substituted alkenyl and alkynyl groups, and substituted-alkyl groups having the structural configuration in which each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hy-- droxy-substituted, alkoxysubstituted, and amino-substituted alkyl, alkenyl, and alkynyl groups, and each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alk-anoxy, halogen, polyoxy groups having the structure in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and amino groups having the structure 15. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 1 to about 250 millimoles per liter of the bisulfite addition product of an u,a'-disubstituted acetylenic compound and 2N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, said compound capable of forming a chaincarryin-g radical being selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula l b SOSM $03M R,

in which M is a cat-ion substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel, each of R R R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted, alkoxy-substituted, and amino-substituted alkyl, alkenyl, and alkynyl groups, and each of R,, and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, polyoxy groups having the structure in which R is a substituent of the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and amino groups having the structure in which each of R and R" are substituents of the group consisting of hydrogen, alkyl, and hydroxyalkyl, and (b) from about 1 to about 25 millimoles per liter of a watersoluble acetylenic compound.

16. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 1 to about 250 millirnoles per liter of a bisulfite addition product selected from the group consisting of 1,4-dihydroxy-2,3-butane- 5 disulfonic acid and the alkali metal, ammonium, magnesium, and nickel salts thereof, and (b) from about 1, to about 20 millimoles per liter of 2-butyne-1,4-diol.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE PROCESS FOR PRODUCING BRIGHT NICKEL DEPOSITS WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION IN WHICH THERE IS DISSOLVED FROM ABOUT 1 TO ABOUT 250 MILLIMOLES PER LITER OF THE BISULFITE ADDITION PRODUCT OF AN A-SUBSTITUTED ACETYLENIC COMPOUND AND 2N TIMES AND EQUIVALENT WEIGHT OF A COMPOUND CAPABLE OF FORMING A CHAIN-CARRYING SULFITE RADICAL, WHERE N IS EQUAL TO THE NUMBER OF ACETYLENIC BONDS PER MOLECULE OF THE ACETYLENIC COMPOUND, SAID BISULFITE ADDITION PRODUCT CONTAINING THE STRUCTURAL CONFIGURATION 